1. Field of the Invention
The present invention relates to the technical area of downwardly mounted slides for drawers, and more particularly to a concealed slide module with the design of a middle plate and having a roof portion and a guide wheel on two sidewalls to improve the stability and reliability.
2. Description of the Related Art
In general, a piece of furniture having a drawer such as a file cabinet, a cupboard and a desk usually comes with a pair of slides connected between the drawer and the furniture to facilitate users to push/pull the drawer to shut or open the drawer, and the slides are provided for carrying the load of the drawer and sliding the drawer. The conventional slide module is mainly divided according to its function and appearance into two main types, respectively: a side-mounted slide module and a downwardly mounted slide module. The side-mounted slide module is mounted onto a side of the drawer and coupled to the furniture, and the downwardly mounted slide module (also known as concealed slide module) is mounted onto the bottom of the drawer and coupled to the furniture to provide a concealed form.
When the concealed slide module is used, the weight of the drawer directly presses on the slide module, and thus its force exertion direction differs from that of the side-mounted slide module. In general, the cross-section of the concealed slide module is substantially in a rectangular shape, which is obviously unlike the long flat cross-section of the general slide module, so that the concealed slide module can bear a relatively larger perpendicular weight, and the concealed slide module comes with a ball design that is different from the design of the side-mounted slide module, and related components have been disclosed in U.S. Pat. No. 8,277,003 entitled “Undermount drawer slide” and invented by Charles A. Milligan and U.S. Pat. No. 8,152,252 entitled “Slide assembly” and invented by Ken-Ching Chen, and both of the aforementioned patents are designed with the structure of a middle plate and an outer plate. With reference to FIG. 1 for a schematic view of the structure as disclosed in U.S. Pat. No. 8,277,003, a roof portion 11 is extended outwardly from both sides of a top side of the middle plate 1, and two abutting surfaces 21 disposed on an inner side of the outer plate 2 and opposite to each other, so that the distance between the outermost sides of the two roof portions 11 is greater than the width of an opening of a ball set 3 for preventing the ball set 3 from falling out while sliding and reducing the gap between the ball set 3 and the middle plate 1 to improve the close contact, so as to achieve the effects of enhancing the sliding smoothness and stability.
In addition, an “Undermount drawer slide” as disclosed in U.S. Pat. Publication No. US 2005/0231083 A1 comprises a wheel installed on two sidewalls of the middle plate separately for replacing the extending structure of the roof portion 11 to improve the sliding smoothness, so that a relatively larger gap is formed between the wheels and the outer plate to provide sufficient moving space. However, the drawers may produce vibrations and noises in practical applications.
It is noteworthy that dimensions and symmetrical positions must be taken into consideration for manufacture the drawer slide with of the design of the dual roof portions 11, and thus having a very high level of difficulty of the manufacture and incurring a high manufacturing cost. On the other hand, the dual wheel design comes with a too-large gap, and thus causing vibrations and noises easily. Obviously, the conventional drawer slides require further improvements.